Blood drawing device with flash detection

ABSTRACT

A device for drawing fluid from a lumen, and particularly blood from a blood vessel, is disclosed. The device may provide indication of the entry of an intravenous cannula into the lumen. The device may include a central body having an outer wall and an inner fluid passage. The device may include a luer-type adapter to permit the attachment of an I.V. infusion set of various lengths (“butterfly needle”) and or any luer-type fitting attached to an existing device. The outer wall of the central body may be transparent or translucent to permit the detection of fluid within the inner fluid passage. A front cannula may extend from one end of the central body and a rear cannula may extend from the other end of the central body. Both the front and rear cannulae may communicate with the inner fluid passage. A flexible sleeve may surround at least a tip portion of the rear cannula. A venting member may be provided near a base portion of the rear cannula between the flexible sleeve and the ambient. The venting member may permit the passage of air through it, but be substantially impermeable to liquids, such as blood.

FIELD OF THE INVENTION

The present invention relates to an apparatus for drawing bodily fluids,and particularly blood, from an animal.

Intravenous blood collection assemblies have long been used to drawbodily fluids, such as blood,.from patients. With respect to drawingblood in particular, the vessel or lumen from which the blood is drawnis often rather small and or not visible. If the needle tip is not incommunication with the interior of the blood vessel during theprocedure, the procedure is likely to be unsuccessful, causing error,undermining the integrity of the specimen, and the patient may be harmedadditionally by the penetration of delicate underlying structures.Accordingly, confirmation of accurate placement of the needle tip into ablood vessel is desirable for blood drawing procedures.

Past intravenous blood collection assemblies have included mechanismsfor indicating when a needle tip is in communication with the interiorof a blood vessel. These needle kits have included a transparent portionin the needle body from which the presence of blood can be observed. Theobservation of blood in the needle body is known as “flash.” Flashdetection has been less than satisfactory for many such collectionassemblies. In some instances, the flow of blood into the transparentportion of the needle body is impeded by air backpressure in the needle,and thus flash confirmation is not visible or delayed. This delay canimpede the determination of the precise moment at which the needle tipenters the blood vessel, which may cause the healthcare worker insertingthe needle to miss or perforate the vessel and penetrate into delicatesurrounding structures. In other instances, while flash occurs, thevisual indication of flash is not easily detected because the amount offlash is small or obscured due to the positioning of the collectionassembly. Accordingly, there is a need for a blood-drawing device thatprovides flash relatively rapidly and to an extent that a user mayreadily detect it.

SUMMARY OF THE INVENTION

Responsive to the foregoing challenges, Applicant has developed aninnovative device for drawing fluid from a lumen, comprising: a centralbody having an outer wall and an inner fluid passage; a front cannulaincorporated into a butterfly needle housing, said front cannulacommunicating with the inner fluid passage at a first. end of thecentral body; a rear cannula communicating with the inner fluid passageat a second end of the central body; a flexible sleeve surrounding atleast a tip portion of the rear cannula; and a means for venting airfrom the flexible sleeve.

Applicant has further developed an innovative device for drawing fluidfrom a lumen, comprising: a central body having an outer wall and aninner fluid passage; a front cannula communicating with the inner fluidpassage; a rear cannula communicating with the inner fluid passage; asleeve surrounding at least a tip portion of the rear cannula; a meansfor venting air disposed between the sleeve and an ambient; and atransparent or translucent member disposed between the front cannula andthe central body.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to assist the understanding of this invention, reference willnow be made to the appended drawings, in which like reference charactersrefer to like elements.

FIG. 1 is an exploded pictorial side view of a first embodiment of thepresent invention.

FIG. 2 is a side view in cross-section of the first embodiment of thepresent invention prior to the insertion of a sample collection tube.

FIG. 3 is a side view in cross-section of the rear cannula portion ofthe first embodiment of the present invention.

FIG. 4 is a side view in cross-section of the first embodiment of thepresent invention after the insertion of a sample collection tube.

FIG. 5A is a side view in cross-section of a second embodiment of thepresent invention incorporated into a Luer-type blood drawing device incombination with a standard hypodermic needle or I.V. infusion set(“butterfly needle”).

FIG. 5B is a side view in cross-section of an alternative Luer-type hubfor use with the Luer-type blood drawing device shown in FIG. 5A.

FIG. 6 is a side view in cross-section of a third embodiment of thepresent invention.

FIG. 7 is a side view in cross-section of the rear cannula portion of afourth embodiment of the present invention.

FIG. 8 is a side view in cross-section of the rear cannula portion of afifth embodiment of the present invention.

FIG. 9 is a side view of a flexible sleeve constructed in accordancewith a sixth embodiment of the present invention.

FIG. 10 is a pictorial view of the venting member and porous spacershown in FIG. 8.

FIG. 11 is a pictorial view of a seventh embodiment of the presentinvention.

FIG. 12 is a pictorial view of the porous collar shown in FIG. 11.

FIG. 13 is a side view in cross-section of a blood flow controlmechanism that may be used with various embodiments of the presentinvention and/or independently in accordance with an eighth embodimentof the invention.

FIG. 14 is a side view in cross-section of a rear cannula portion of aninth embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Reference will now be made in detail to a first embodiment of thepresent invention, an example of which is illustrated in theaccompanying drawings. With reference to FIG. 1, an exploded pictorialview of a blood-drawing device 10 is shown. The blood-drawing device 10includes a front cannula 130, a central body 100, a venting member 160,a rear cannula 140, and a flexible sleeve 150. A guide tube 116 may beconnected to the central body 100. The front cannula 130 and the rearcannula 140 may each have a generally elongated cylindrical bodydefining an elongated fluid passage extending from one end of thecannula to the other end. The front cannula 130 may extend from thefront end of the central body 100 and terminate at a tapered or pointedend 132, which is adapted to be inserted into a lumen. The rear cannula140 may extend from the rear of the central body 100 and terminate at atapered or pointed end 142. The sleeve 150 may isolate the rear cannula140 from the ambient, wherein the ambient includes any space outside ofthe sleeve 150, irrespective of whether or not the space is containedwithin the guide tube 116 or any other structure.

With reference to FIGS. 1 and 2, the central body 100 may include one ormore constituent elements, such as a threaded connector 112, which maybe integrally formed with, or connected to the central body usingadhesive, male-female interfaces, threaded interfaces, or any otherconnection means. The central body 100 may include an annular ring 104,radiating fins 105, or like features, extending from the central bodyand which may be adapted to aid a user in handling the device 10. Afluid passage 110 within the central body 100 may communicate with, andin the embodiment shown, be connected to, the inner portion.134 of thefront cannula 130 and the inner portion 144 of the rear cannula 140,respectively, using adhesive, threaded interfaces, pressure fit, orother connection means. Alternatively, the central body 100 may beintegrally formed with the front and/or rear cannulae 130 and 140. It isalso appreciated that the front and/or rear cannulae may be transparentor translucent, in whole or part, to provide flash detection inalternative embodiments of the present invention. The fluid passage 110may be defined by the opening within the central body between the frontand rear cannulae when the cannulae are directly connected to thecentral body. The fluid passage 110 may be adapted to receive asufficient amount of fluid to allow observation of the-fluid (i.e.,“flash”) from outside the blood-drawing device 10. At the same-time, thefluid passage 110 may have a sufficiently small volume so as to rapidlyfill with fluid during the use of the blood-drawing device.

Preferably, the central body 100 may be constructed of plastic materialsuitable for medical use. Further, in the first embodiment of thepresent invention, all, or portions, of the central body 100 may betransparent, translucent, connected to transparent or translucent I.V.tubing, or otherwise adapted to permit detection of fluids passingthrough the central body and/or I.V. tubing from a vantage point outsideof the blood-drawing device 10. For example, with particular referenceto FIG. 1, the central body 100 may include a transparent wall that isadapted to permit the observation of “flash” when it occurs. In analternate embodiment of the present invention, the side wall of thecentral body 100 also may be adapted to magnify or otherwise enhance thedetection of fluid passing through the central body, although it isappreciated that a magnifying or enhancement feature is not necessarilyrequired.

With particular reference to FIG. 2, the-venting member 160 (i.e., ameans for venting air) may be inserted over the rear cannula 140 andpressed against or near to the rear portion of the central body 100(i.e., the portion proximate to the rear cannula 140). The ventingmember 160 may form a seal against the rear cannula that is sufficientto prevent blood from escaping past the venting member. In the firstembodiment of the present invention, the venting member 160 may be gas,and particularly air, permeable, but at least partially impermeable to aliquid, such as blood. Preferably, the venting member 160 may besubstantially porous for gas constituents less than about 5 microns insize, and substantially non-porous for liquid constituents about 5microns or greater in size, however, it is appreciated that theseapproximate sizes should not be limiting for the invention. The ventingmember 160 may be constructed of any of a number of materials thatprovide the desired level of porosity, which may include, but are notlimited to sintered, layered, rolled, foamed, perforated, orimpregnated, hydrophyllic/hydrophobic compositions, porous polyethylene,porous polypropylene, porous polyfluorocarbon, absorbent paper,materials impregnated with dilute Russell Viper venom molded fiber,fiberglass, felt, granular starch, cellulose, polyacrylamide gel,hydrogel, a molded admixture of porous hydrophobic/hydrophyllic granulesand sufficiently low density silicone, molded open cell polyurethane,and like polymeric materials. Examples of materials that may be used toconstruct the venting (i.e., porous) member 160 are discussed in U.S.Pat. No. 4,207,870 to Eldridge, and U.S. Pat. No. 4,340,068 to Kaufman,each of which are hereby incorporated by reference. The venting member160 shown in FIG. 2 includes a base portion nearest the central body100, a tapered portion furthest from the central body, and an annularrecess in between the tapered portion and the central body. The taperedportion may facilitate the insertion of the flexible sleeve 150 over theventing member 160 and the annular recess may facilitate retention ofthe flexible sleeve after it is so inserted. It is also appreciated thatthe venting member 160 may have any shape in alternative embodiments, beit cylindrical, spherical, tapered, irregular, or other.

The rear cannula 140 may communicate with,.and in the embodiment shown,extend out of, the central body 100, and through the venting member 160.The rear cannula 140 may terminate at a tapered or pointed end 142,which is adapted to be inserted into a fluid sample tube (shown in FIG.4), or connected to a fluid collection reservoir. A flexible sleeve 150may be disposed over and around the rear cannula 140. The flexiblesleeve 150 may be stretched over the tapered portion on the end of theventing member 160, or in alternate embodiments, otherwise contact theventing member 160. The flexible sleeve 150 may be made of a shapememory material, such as elastic rubber or elastomeric silicone orlatex, or the like, which will return to the shape shown in FIG. 2 aslong as no other structure obstructs it. Examples of materials that maybe used to construct the flexible sleeve 150 are discussed in U.S. Pat.No. 3,877,465 to Miyake, U.S. Pat. No. 5,086,780 to Schmitt, U.S. Pat.No. 6,110,160 to Farber, U.S. Pat. No. 6,533,760 to Leong, U.S. PatentPub. No. US 2002/0004647 A1 to Leong, and U.S. Patent Pub. No. US2003/0078544 A1 to Chen, each of which is hereby incorporated byreference. It is appreciated that any suitable material may be used forthe flexible sleeve without departing from the intended scope of thepresent invention.

A generally cylindrical guide tube 116 may be connected to the threadedconnector 112 by interlocking threads 114 and 120, respectively. Whenconnected to the central body 100, the guide tube 116 may have an openend 118 adapted to receive a fluid sample container (shown in FIG. 4).The guide tube 116 may extend coaxially with the rear cannula 140sufficiently beyond the tapered end 142 of the rear cannula to providesome degree of protection against inadvertent “needle sticks” by a userof the blood-drawing device 10 as well as to guide the reception of afluid sample container.

The function of the first embodiment of the blood-drawing device 10 willnow be described with reference to FIGS. 2-4. With reference to FIG. 2,the tapered end 132 of the front cannula 130 (or some extension thereof)may be inserted into a fluid containing body lumen prior to theinsertion of a fluid sample container into the guide tube 116. In apreferred embodiment of the present invention, the front cannula 130 isinserted into a lumen containing a visually detectable fluid, such asblood. At the time that the front cannula 130 is inserted into the bodylumen, it is assumed that the internal passages within the blood-drawingdevice (i.e., the passage through the front cannula 130, the fluidpassage 110, the passage through the rear cannula 140, and the spaceinside the flexible sleeve 150) may be filled with atmospheric air orsome other gas. When the front cannula 130 establishes communicationwith the fluid in the body lumen, fluid pressure in the lumen may forcethe fluid through the front cannula 130 towards the fluid passage 110.

With reference to FIG. 3, the flow of fluid 200 through the frontcannula may begin to compress the air in the fluid passage 110, the rearcannula 140, and the space between the rear cannula and the flexiblesleeve 150, driving the air towards the Venting member 160. As bloodflows into the device, all or a portion of the air in the device mayflow through venting member 160 (i.e., be vented) because the ventingmember is gas permeable. As a result, there may be insufficient airpressure within the fluid passage 110 to resist the flow of the fluid200 into the fluid passage 110, where it may be detected or observed as“flash” by a user. It is appreciated that “flash” may be detected at anypoint along the device that includes a transparent or translucentmember, which may include, but not be limited to, a transparent ortranslucent cannula, central body, I.V. tubing, flexible sleeve, orother constituent member. After fluid fills the blood drawing device 10and reaches the venting member 160, fluid leakage past the ventingmember may be prevented or reduced because the venting member may be atleast partially impermeable to liquids, such as blood. As a result, theblood drawing device 10 may provide for detection of “flash” when thefront cannula 130 is inserted into a body lumen (such as a vein)containing fluid (such as blood) to be withdrawn prior to the insertionof a fluid sample container into the guide tube 116 and the penetrationof the rear cannula into the fluid sample container.

With reference to FIG. 4, after the detection of “flash” within thefluid passage 110, a fluid sample container 170 may be used to collect asample of the fluid flowing from the body lumen. The fluid samplecontainer 170 may have a generally cylindrical outer wall, which ispreferably, but not necessarily, transparent. The outer wall may definea collection chamber 174, which is preferably maintained in a vacuumcondition prior to use of the container 170. A stopper 172 may be usedto seal the open end of the container 170 so as to prevent air leakageinto the collection chamber 174 prior to use of the container. Oneexample of a commercially available vacuum container that may be usedwith various embodiments of the invention is a Vacutainer sold by BectonDickinson & Co. of Franklin Lakes, N.J. Construction of vacuumcontainers, such as the one noted above, and the selection of materialstherefore, are well known in the art.

In order to collect a fluid sample, the container 170 may be slid intothe guide tube 116 through the opening 118 until it contacts theflexible sleeve 150. As the container 170 is pushed further into theguide tube 116, the tapered end 142 of the rear cannula presses into andpierces both the flexible sleeve 150 and the stopper 172. The flexiblesleeve is pushed down towards, and may gather around, the venting member160, as shown in FIG. 4. When the tapered end 142 of the rear cannula140 is past the stopper 172, the pressurized fluid in the body lumen mayreadily flow through the blood-drawing device 10 to the vacuum space inthe collection chamber 174.

After a first container 170 is full of fluid, it may be removed from theblood drawing device 10 for replacement by a second container. As thefirst container 170 is withdrawn from the guide tube 116, the flexiblesleeve 150 may follow until it regains its original shape because it isconstructed of shape memory material. The openings in the stopper 172and the flexible sleeve 150, which were created by the rear cannula 140,may collapse or “heal” when the rear cannula is removed due to thenature of the material used to construct the stopper and the flexiblesleeve. As a result, the fluid sample in the first container 170 may besealed within it, and the fluid within the flexible sleeve 150 may beprevented from substantially leaking out of it. Thereafter, a secondcontainer 170 may be inserted into the guide tube 116 for collection ofa fluid sample in the manner described above.

A second embodiment of the present invention is shown in an explodedside view in FIG. 5A. With reference to FIG. 5A, a Luer-typeblood-drawing device is provided with a venting member 160. The centralbody 100 may be provided with an enlarged fluid passage 110 which mayimprove flash visibility. It is appreciated that the enlarged fluidpassage could have any of a number of different shapes and sizes, whichmay be uniform or non-uniform over the length of the passage. It isfurther appreciated that the fluid passage 110 in each embodiment of theinvention described herein, could have any of a variety of shapes andsizes without departing from the intended scope of the invention.

The butterfly needle 180 may be connected to the Luer-type hub 102 via abutterfly connection tube 182. The butterfly needle 180 may include abutterfly (i.e., front) cannula 184 and one or more wings 186. Thebutterfly cannula 184 may be inserted directly into the body lumen forblood collection. Flash may be observed in the transparent ortranslucent butterfly connection tube 182, in which case the centralbody 100 need not be transparent or translucent (although it could be).

With continued reference to FIG. 5A, known butterfly needles may use abutterfly connection tube 182 approximately 12 or more inches in length.This length of tubing is used so as to provide a sufficiently longcolumn of air to permit flash observation when the blood-drawing device10 is not provided with an air vent. Specifically, when a butterflyconnection tube is used without an air vent, the flow of fluid throughthe butterfly needle may compress the volume of air in the butterflyconnection tube 182, the fluid passage 110, the rear cannula 140, andthe space between the rear cannula and the flexible sleeve 150. Becausethere is no-vent provided, as blood flows into the device, the air inthe device exerts an increasing level of backpressure on the blood,which may prevent blood flow and flash detection. The inclusion of abutterfly connection tube approximately 12 inches in length or greaterincreases the relative volume of air in the blood collection device. Theincreased volume of air in the device may permit flash detection beforethe air backpressure in the device rises to a level that preventsfurther blood flow into the device and could frustrate flash detection.Butterfly connection tubes of this length may be coiled in packaging,and retain some coil memory after they are removed from their packaging.Previously coiled butterfly connection tubes may resist beingstraightened for use and have an inherent bias towards returning totheir coiled shape. Accordingly, manipulation of a butterfly needleattached to a previously coiled butterfly connection tube may bedifficult due to the connection tube's tendency to recoil. This actioncan be the cause of accidental needle sticks for the healthcare workerand the patient. Furthermore, the coil memory of the tubing may makehandling generally difficult for lumen insertion, and/or maintenance ofthe needle in the lumen.

The butterfly connection tube 182 used in the device shown in FIG. 5Amay be less than approximately 12 inches in length, and more preferably,may be only a few inches in length as a result of the inclusion of aventing member 160 in the blood-drawing device 10. The inclusion of theventing member 160 may obviate the need for a relatively long column ofair in the butterfly connection tube that otherwise may be needed toindicate flash. The use of a shortened butterfly connection tube 182 mayalso obviate the need to coil the tube prior to use, thereby eliminatingthe issues associated with coil memory in the tube, as well as make itpossible to use rigid or semi-rigid connection tubes that may betterenable placement of the front cannula into the body lumen.

With reference to FIG. 13, a butterfly needle 180, such as shown in FIG.5A, may optionally be provided with a blood flow control member 190. Theblood flow control member 190 may include a slideable control valve 188surrounding the distal end of the butterfly connection tube 182 and thebutterfly cannula 184. The slideable control valve 188 may include aninner convex boss 189 adapted to restrict flow through the butterflycannula 184 when positioned near the inner butterfly cannula end 185.Flow through the butterfly cannula 184 may be controlled by manuallysliding the control valve 188 so that the inner convex boss 189 isnearer to or more removed from the inner butterfly cannula end 185. Theslideable control valve 188 may completely or partially shield thedistal end of the butterfly cannula 184 when it is-positioned to blockor restrict flow through the butterfly cannula. Control over blood flowthrough the butterfly cannula 184 maybe used to avoid collapsing smallor low pressure lumens (typical of children and the elderly) duringnegative pressure conditions experience during blood drawing procedures.It is appreciated that the blood flow control member 190 couldoptionally be used with other embodiments of the present invention thatdo not incorporate a butterfly needle. It is also appreciated that theflow control member 190 may be used with any conventional I.V. infusionor fluid drawing device. It is further appreciated that alternativecontrol valve 188 designs are known in the art and may be substitutedfor the afore-described design without departing from the intended scopeof the present invention.

It is further appreciated that in an alternative embodiment of thepresent invention shown in FIG. 5A, the butterfly needle 180 may bemodified to eliminate the butterfly wings 186 without departing from theintended scope of the invention. More specifically, the embodiment shownin FIG. 5A could be modified so that the butterfly cannula 184 isreplaced by a conventional front cannula, which may be connected to thecentral body 100 by any elements, including but not limited to aflexible tube, rigid tube, or semi-rigid tube, any one of which may beconstructed of transparent or translucent material to indicate flash.

A variation of the embodiment of the present invention shown in FIG. 5Ais shown in FIG. 5B, in which the butterfly needle 180 is replaced by afront cannula 130 connected directly to the Luer-type hub 102. TheLuer-type hub 102 is adapted to connect to the Luer-type central body100 in accordance with known methods.

A third embodiment of the present invention is shown in FIG. 6. Withreference to FIG. 6, a porous member 160 may be inserted over the rearcannula 140 and slightly separated from the rear portion of the centralbody 100 (i.e., the portion proximate to the rear cannula 140), leavinga small space 161 between the central body and the porous member. Theporous member 160, itself, and/or the seal it forms against the rearcannula, may not completely prevent blood from escaping past the porousmember. In such instances, the porous member 160 may be constructed ofmaterial that is porous to gas (air) and somewhat, but not perfectly,non-porous to blood. The porous member 160 may preferably include atapered portion, however, it is appreciated that the porous member mayhave any alternative shape, such as cylindrical, spherical, irregular,or the like, without departing from the intended scope of the invention.

In embodiments in which the porous member 160 is not completelynon-porous to blood, a gas or air porous and/or liquid absorbent spacer168 may be inserted behind the porous member 160 in the space 161. Theporous spacer 168 may be constructed of any of a number of materialsthat are porous to gas (air), and partially, substantially, orcompletely non-porous to liquids such as blood, and/or partially orcompletely absorbent of such liquids. For example, the porous spacer 168may be constructed of sintered, layered, rolled, foamed, perforated, orimpregnated hydrophyllic/hydrophobic compositions, porous polyethylene,porous polypropylene, absorbent paper, molded fiber fiberglass, felt,granular starch, cellulose, polyacrylamide gel, hydrogel, or the like.It is appreciated that in some embodiments the porous spacer 168 maypermit some blood seepage past it, however, it is expected that theporous spacer may reduce or slow such seepage. After the porous spacer168 is positioned in the airspace 161, the flexible sleeve 150 may bestretched over-the porous member 160 and a portion, or none, of theporous spacer 168, so long as at least of portion of the porous spacerremains in communication with the ambient.

A fourth embodiment of the present invention is shown in FIG. 7. Withreference to FIG. 7, a rear cannula 140, non-porous member 162, and airspace 161 arrangement, similar to that shown in FIG. 6, are used. Theflexible sleeve 150 is modified from that-shown in earlier embodimentsto include a side tubulation 154 and a porous insert 152. The porousinsert 152 may be any size and may be constructed of sinteredpolyethylene, perforated plastic, porous fiber, rolled fiber, or thelike. It is appreciated that in some embodiments the porous insert 152may permit some blood seepage past it, however, it is expected that theporous insert may-reduce or slow such seepage. As a result of theinclusion of the porous insert 152 between the interior of the sleeve150 and the ambient, air in the blood-drawing device 10 may vent fromthe interior of the sleeve through the porous insert 152 when the deviceis used to draw blood. Blood within the sleeve 150 may be preventedhowever, at least initially, from passing the porous insert 152.

A fifth embodiment of the present invention is shown in FIGS. 8 and 10.With reference to FIGS. 8 and 10, a non-porous venting member 166 may beinserted over the rear cannula 140 and slightly separated from the rearportion of the central body 100 (i.e., the portion proximate to the rearcannula 140), by a porous spacer 168 between the central body and thenon-porous venting member. The non-porous venting member 166 may form aseal against the rear cannula that is sufficient to prevent blood fromescaping past the non-porous venting member along its surface in contactwith the rear cannula. The non-porous venting member 166 may beconstructed of material, such as plastic suitable for medical use, whichis non-porous to both gas (air) and blood. The outer surface of thenon-porous venting member 166 may include one or more grooves, channels,bumps, or like features 167 (collectively “venting features 167”) thatpermit the passage of air. It is appreciated that the venting features167 may be very small (of a size capable of permitting the passage ofair molecules). Such small venting features may inherently restrict thepassage of blood Molecules, which typically may be larger that airmolecules. The non-porous venting member 166 may preferably have atapered tip and adapted to receive a flexible sleeve 150 stretched overit.

A porous spacer 168 may be inserted between the non-porous ventingmember 166 and the central body 100. The porous spacer may beconstructed of any of a number of materials that are porous to gas(air), and partially, substantially, or completely non-porous to liquidssuch as blood. For example, the porous spacer 168 may be constructed ofsintered polyethylene, perforated plastic, porous fiber, rolled fiber,or the like. It is appreciated that in some embodiments the porousspacer 168 may permit some blood seepage past it, however, it isexpected that the porous spacer may reduce or slow such seepage.

With continued reference to FIGS. 8 and 10, the flexible sleeve 150 maybe stretched over the non-porous venting collar 166 and at least aportion of the porous spacer 168 such that at least of portion of theporous spacer remains in direct communication with the ambient. Air inthe blood drawing device may vent from the interior of the sleeve 150past the venting features 167 on the non-porous venting member 166 andthrough the porous spacer 168 to the ambient when the device is used todraw blood. Blood within the sleeve 150 may be prevented however, atleast initially, from passing the porous spacer 168 as a result of thenature of the material in the porous spacer and the relatively smallpassageways provided by the venting features 167.

A sixth embodiment of the present invention is shown in FIG. 9. Withreference to FIG. 9, an air-permeable, completely or partiallyblood-impermeable flexible sleeve 151 is provided. The air-permeablesleeve 151 may be used in conjunction with or independently of theabove-referenced embodiments of the present invention. A known flexiblesleeve is described in. U.S. Pat. No. 3,877,465 to Miyake, incorporatedby reference above. In the present embodiment of the invention, theelastic sheath material making up the wall of the sleeve 151 may beconstructed of a material that is largely air-permeable, but partially,largely or entirely impermeable to blood. The air-permeable sleeve 151may be used to isolate the rear cannula 140 of a blood drawing devicefrom the ambient in the same manner as conventional sleeve may isolaterear cannulae. During a blood drawing procedure using a device notequipped with a means for venting air from the sleeve, blood from alumen may be slowed or prevented from entering the device due to airback pressure in the device. In these devices the air in the device maybe trapped because there is no vent provided. In the present embodiment,an air-permeable sleeve 151 replaces a conventional sleeve on the blooddrawing device. The air-permeable sleeve 151 may provide a pathway tovent air from the device interior, through the sleeve wall, to theambient. As the air is vented, the blood filling the device may contactthe air-permeable sleeve 151. However, the air-permeable sleeve 151 mayprevent or retard the flow of blood through its wall because the poresize of the air-permeable sleeve may be large enough to allow thepassage of air, but too small to allow much or any blood to pass. Thisair passage-blood blockage may permit blood to fill the needle and/orthe sleeve 151 more readily because there is reduced or no air backpressure inhibiting the flow of blood into the blood drawing device. Asa result, a blood drawing device equipped with the air-permeable sleeve151 may indicate flash (the visual indication of blood flow into theneedle) more readily. The air-permeable sleeve 151 may be used withconventional needle drawing or infusion sets (such as butterflyneedles), hypodermic needles, or the like, to enhance flash indication.

The air-permeable sleeve 151 may be made of any suitable material thatis completely or at least partially air-permeable and substantiallyblood impermeable, such as for example, low density polyethylene or lowdensity rubber. One example of a method of making such material isdescribed in U.S. Pat. No. 5,641,442. A second example may be made ofcrumbed material of sufficiently low density/high flexibility to allowthe required flexibility in spite of the use of thermal binders likepolyethylene. Low density material such as low density silicone may besifted using a #80 mesh and mixed with #100 mesh low densitypolyethylene. This mixture may be heated at approximately 280° F. andinjected into a cavity mold to form the selectively porous sleeve 151.

An air-permeable sleeve may be constructed of porous materialformed-from the combination of a hydrophobic porous material with ahydrophilic porous agent. The hydrophobic porous material, for example,may be a polymeric matrix of either thermoplastic resins such aspolyvinyl chloride or copolymers thereof, or synthetic or naturalthermosetting rubber-like polymers. In a second example, the polymericmatrix may be rubber-like polymers combined with additives such asanti-degradants, cross-linking agents, cure inhibitors, platinum andother type catalysts, inert fillers, or like materials used to compoundthermosetting compounds, and intimately mixed with a hydrophilic porousagent such as silica hydrogel, precipitated hydrated silica, for examplesuch as that sold under the trademark Hi-Sil from PPG Industries, orpolyacrylamide gel, cross-linked homopolymer of acrylamide, for examplesuch as that sold under the trademark Agrosoake from AgrosoakeInternational, inert fillers and/or water or solvent soluble porosics.In a third example, the polymeric matrix may be made of a synthetic ornatural thermosetting polymer or copolymer, such as those that may bemade in accordance with the methods disclosed in U.S. Pat. No. 4,548,835to Takahashi, et al. and U.S. Pat. No. 4,153,760 to Sundberg et al, forexample, each of which is hereby incorporated by reference.

The porous agent may be prepared by polymerizing acrylamide in thepresence of an aqueous sodium carbonate to produce a partiallyhydrolyzed, lightly cross-linked, polyacrylamide gel in accordance withthe method disclosed in U.S. Pat. No. 3,022,279 to Proffit, for example,which is hereby incorporated by reference. The polyacrylamide gel may beproduced in bead or granular form using an inverse suspensionpolymerization method for water-soluble monomer, which is disclosed inU.S. Pat. No. 2,982,749 to Friedrich et al., for example, and which ishereby incorporated by reference.

In one embodiment, for example, the hydrophilic granules may be added tothe hydrophobic material in sufficient quantities to create ahydrophilic/hydrophobic porous material. The porosity of the hydrophobicmaterial may be manifested by a network of voids/pores extendingthroughout the matrix or binder, between neighboring particles of thedispersed filler and portions of the polymeric matrix, which may beachieved by the shrinking of the swollen hydrophilic granules during thedehydration/curing phase. The resultant degree of porosity may becontrolled by the amount of water or water substitute added to thepolymeric matrix binder material during the mixing phase, thevulcanization of the polymeric matrix (such as for example, underhydrostatic conditions in a steam autoclave to a state of cure using thepressurized steam as a source of heat), the proportion and size of thehydrophilic granules added, the duration of the mixing phase, and thewall thickness of the elastomeric sleeve. The hydrophilic granules maybe mixed with a normally hydrophobic binder (and water or a watersubstitute may be added to control porosity) in a mixing type extruder.

When this material is formed into an air-permeable flexible sleeve 151,water-based liquids such as blood may rapidly soak into the pores/voidscontaining the granular material, causing the granules to swell and sealthe pores/voids contained within the polymeric matrix. Thus, theair-permeable flexible sleeve, which is initially permeable to air, maybecome relatively impermeable to liquids, such as blood, due to theswelling of the moisture reactive granules entrapped within thepores/voids within the polymeric matrix.

A seventh embodiment of the present invention is shown in FIGS. 11 and12. With reference to FIGS. 11 and 12, a flexible sleeve 150 may beprovided with one or more openings or perforations 156 extending throughthe wall of the sleeve. The openings 156 may be relatively small, onlyneeding to be capable of permitting the passage of air molecules. Aporous collar 157 constructed of sintered polyethylene, perforatedplastic, porous fiber, rolled fiber, or the like, may be provided overthe openings 156. The flexible sleeve 150 may be stretched over thenon-porous member inserted over the rear cannula, (such as non-porousmember 162 shown in FIG. 7). Air in the blood drawing device may ventfrom the interior of the sleeve 150 past the openings 156 in theflexible sleeve wall and through the porous collar 157 to the ambientwhen the device is used to draw blood. Blood within the sleeve 150 isprevented however, at least initially, from passing the porous collar157 as a result of the nature of the material making up the porouscollar and potentially by the relatively small passageways provided bythe openings 156.

An alternative embodiment of the present invention is shown in FIG. 14,in which the venting member 160 is spaced from the central body 100 andthe flexible sleeve 150 envelopes the entire side wall of the ventingmember. A portion of the base end wall of the venting member 160 isexposed to the ambient to permit air to vent. In a further altemative, aporous spacer 168 maybe disposed in the air space 161 to block or absorbany blood seepage past the venting member.

Each of the embodiments of the present invention shown in all of theafore-noted figures may also utilize a transparent or translucentflexible sleeve 150 to provide flash detection. An example of atransparent sleeve is disclosed in U.S. Pat. No. 3,886,930 to Ryan,which is hereby incorporated by reference. Use of a transparent ortranslucent sleeve 150 may make it unnecessary for the central body 100or other elements of the device to be constructed of transparent ortranslucent material because the flash may be detected through the wallof the sleeve itself and thereby allow for the retrofitting of knownblood-drawing devices to provide air venting and flash detection withoutother modification of the device. Use of a transparerit or translucentsleeve 150 may also obviate the need to have discreet front and rearcannulae 130 and 140. The front and rear cannulae may be constructedfrom a single integral piece of material because in this embodiment ofthe invention there may be no need to view flash in the central body100.

Each of the embodiments of the invention described above may also bemodified such that the porous member 160 (FIGS. 1-6), the porous collar157 (FIGS. 11-12), the porous insert 152 (FIG. 7), or the porous spacer168 (FIGS. 6, 8 and 10) includes or is constructed of any one or more ofa number of substances that may permit air venting, and limit and reduceblood seepage, but not completely prevent blood seepage through theparticular porous structure. Such materials include absorbent pleated orrolled paper, molded fiber or fiberglass, felt, sintered compositions ofhydrodphilic/hydrophobic materials such as polyethylene andpolyacrylamide gel, and/or any other material capable of venting air butimpeding the passage of liquids.

For example, hydrophilic and/or hydrophobic substances such aspolyethylene and granular starch, cellulose, polyacrylamide gel, or thelike may be used. Such substances are known in the art, and may be usedto permit gas (e.g., air) to flow through them, but absorb or blockliquid substances. Accordingly, a porous member, collar, insert, orspacer, comprised of these materials may be used to permit the air in ablood drawing device to vent past it until it is contacted by a liquid,such as blood, at which time the blood may be absorbed.

Similarly, glass powder or fiber may be used to simulate clotting, or aclotting agent, such as dilute Russell Viper Venom, may be used topermit air venting with little or reduced blood seepage. Russell ViperVenom is known in the art as a clotting agent. A porous member, collar,insert, or spacer impregnated with a clotting agent or simulatingclotting agent may be used to permit the air in a blood drawing deviceto vent until it is contacted by blood, at which time the blood may clotor act as clotted and reduce further blood seepage through the porousmember, collar, insert or spacer. As a result, use of hydrophilic and/orclotting agents in the previously described porous member, collar,insert, or spacer may permit improved blood flow into a blood drawingdevice and flash detection.

A multitude of different means for venting air are described above. Itis appreciated that various embodiments of the invention may include anytype of means for venting air disposed between a flexible sleevecovering the rear cannula of a blood drawing device and an ambient,including, but not limited to one or more air porous materials providedindividually or in combination, and/or combinations of air porous andnon-air porous materials.

It will be apparent to those skilled in the art that variations andmodifications of the present invention can be made without departingfrom the scope or spirit of the invention. For example, the shape, size,and material selection for the various components of the blood-drawingdevice may be changed without departing from the intended scope of theinvention and appended claims. It is further appreciated that formingone or more elements of the apparatus embodiments of the presentinvention integrally as opposed to separately is intended to fall withinthe scope of the invention and appended claims.

1-27. (canceled)
 28. A device for assisting in drawing fluid from alumen while providing for flash detection of the fluid, said devicecomprising: a flexible sleeve having an open end, a wall defining aninterior space, and being adapted to surround at least a tip portion ofa cannula provided by a fluid drawing device; and a means for ventingair from the sleeve interior space, said means for venting air beingdisposed at least partially in the open end of the sleeve, being adaptedto reside at least partially between the sleeve wall and said cannula,and being at least partially blood impermeable.
 29. The device of claim28 wherein the flexible sleeve is at least partially transparent ortranslucent.
 30. The device of claim 29 wherein the means for ventingair comprises material selected from the group consisting of: sinteredcompositions, layered compositions, rolled compositions, foamedcompositions, perforated compositions, impregnated compositions,hydrophyllic compositions, hydrophobic compositions, sinteredpolyethylene, porous polyethylene, porous polypropylene, porouspolyfluorocarbon, absorbent paper, materials impregnated with diluteRussell Viper venom, molded fiber, fiberglass, felt, granular starch,cellulose, polyacrylamide gel, hydrogel, a molded admixture of poroushydrophobic/hydrophyllic granules and low density silicone, and moldedopen cell polyurethane.
 31. The device of claim 28 wherein the means forventing air comprises material selected from the group consisting of:sintered compositions, layered compositions, rolled compositions, foamedcompositions, perforated compositions, impregnated compositions,hydrophyllic compositions, hydrophobic compositions, sinteredpolyethylene, porous polyethylene, porous polypropylene, porouspolyfluorocarbon, absorbent paper, materials impregnated with diluteRussell Viper venom, molded fiber, fiberglass, felt, granular starch,cellulose, polyacrylamide gel, hydrogel, a molded admixture of poroushydrophobic/hydrophyllic granules and low density silicone, and moldedopen cell polyurethane.
 32. The device of claim 28 wherein the means forventing air comprises a porous member having an inner opening adapted toreceive a cannula, a tapered outer portion, and an annular recessadjacent the tapered outer portion.
 33. The device of claim 28 furthercomprising: a central body having an outer wall and an inner passage;and a cannula extending from said central body passage, wherein saidsleeve surrounds at least a tip portion of the cannula, and wherein saidmeans for venting air is disposed at least partially in the open end ofthe sleeve and is adapted to reside at least partially between thesleeve wall and said cannula.
 34. The device of claim 33 wherein themeans for venting air includes a porous member, a porous collar, aporous insert, or a porous spacer.
 35. The device of claim 28 whereinthe means for venting air includes a porous member, a porous collar, aporous insert, or a porous spacer.
 36. The device of claim 33 whereinthe means for venting air includes a base portion contacting the centralbody.
 37. The device of claim 33 wherein the means for venting airincludes a base portion spaced from the central body.
 38. The device ofclaim 37 further comprising a porous spacer comprising absorbentmaterial disposed between the base portion and the central body.
 39. Thedevice of claim 33 wherein at least a portion of the central body istransparent or translucent.
 40. The device of claim 28 wherein the meansfor venting air is substantially impermeable to blood.
 41. The device ofclaim 28 wherein the means for venting air comprises: a first memberadapted to vent air; and a second member adapted to absorb blood. 42.The device of claim 28 wherein the means for venting air includes ablood clotting agent.
 43. The device of claim 28 wherein the means forventing air comprises: a first member including one or more ventingfeatures, said first member contacting a base portion of the cannula;and a porous spacer disposed between the non-porous member and thecentral body.
 44. The device of claim 33 wherein the central bodyincludes means for magnifying an image of fluid within the central body.45. The device of claim 28 wherein the means for venting air issubstantially porous for gas constituents less than about 5 microns insize, and substantially non-porous for liquid constituents about 5microns or greater in size.
 46. The device of claim 33 furthercomprising a front cannula connected to the central body.
 47. The deviceof claim 46 further comprising a flexible or semi-rigid tube connectingthe front cannula to the central body.
 48. The device of claim 47further comprising a means for controlling blood flow through the frontcannula.
 49. The device of claim 33 wherein the sleeve is at leastpartially transparent or translucent.
 50. The device of claim 28 furthercomprising: a central body having an outer wall and an inner fluidpassage; a front cannula incorporated into a butterfly needle housing,said front cannula communicating with the inner fluid passage at a firstend of the central body; and a rear cannula communicating with the innerfluid passage at a second end of the central body, wherein said sleevesurrounds at least a tip portion of the rear cannula, and wherein saidmeans for venting air is disposed at least partially in the open end ofthe sleeve and is adapted to reside at least partially between thesleeve wall and said rear cannula.
 51. The device of claim 50 whereinthe means for venting air includes a porous member, a porous collar, aporous insert, or a porous spacer.
 52. The device of claim 50 whereinthe means for venting air includes a base portion contacting the centralbody.
 53. The device of claim 50 wherein the means for venting airincludes a base portion spaced from the central body.
 54. The device ofclaim 53 further comprising a porous spacer comprising absorbentmaterial disposed between the base portion and the central body.
 55. Thedevice of claim 50 wherein at least a portion of the central body istransparent or translucent.
 56. The device of claim 50 furthercomprising a means for controlling blood flow through the front cannula.57. The device of claim 50 wherein the sleeve is transparent ortranslucent.
 58. The device of claim 50 wherein the means for ventingair is a porous member that includes a tapered portion and an annularrecess adjacent the tapered portion.
 59. The device of claim 50 whereinthe front cannula is connected to the central body by a transparent ortranslucent tube.
 60. The device of claim 50 wherein the butterflyneedle housing includes a transparent or translucent portion for flashdetection.
 61. The device of claim 28 further comprising: a central bodyhaving an outer wall and an inner fluid passage; a front cannulacommunicating with the inner fluid passage at a first end of the centralbody; and a rear cannula communicating with the inner fluid passage at asecond end of the central body, wherein said sleeve surrounds at least atip portion of the rear cannula, and wherein said means for venting airis disposed at least partially in the open end of the sleeve and isadapted to reside at least partially between the sleeve wall and saidrear cannula.